1. Field of the Invention
This invention relates generally to an apparatus and a method for guiding an electric discharge and particularly to a laser guided discharge device capable of guiding a discharge current between two electrodes using only laser light and no guiding wall.
2. Description of Related Art
Traditional "wall-guided" gas discharge tubes used for example as laser tubes, flashlamps and fluorescent tubes guide an electric discharge between two electrodes by an inner wall of a tube. The inner wall of the tube must be made of electrically insulating materials such as glass or ceramic in order to avoid shorting out the electric discharge. In addition, in order to prevent corrosion and consequently prolong the life of the tube, the inner wall of the tube must be made of materials that do not chemically react with the gas. Satisfying these two requirements severely limits the types of materials which can be used to make discharge tubes. For example, metals such as steel, tungsten and nickel cannot be used to guide an electric discharge between electrodes in "wall-guided" discharge tubes even though they possess particular advantages for housing gases such as high impact resistance, longevity, design flexibility and scalability because they are not electrically insulating. Also, if the gas is a metal vapor, for example, an alkali (group IA of the periodic table), alkaline earth metals (group IIA of the periodic table) or some other transition element (groups IIIA to VIIIA, IB and IIB), no tube known to the inventor can be used to guide the electric discharge. This is mainly because eventually atoms in the gas will accumulate on and chemically or physically attack the inner walls of the tube and will short out or destroy the walls and other components of the device (tube). Further, typical gas discharge tubes can be damaged or destroyed due to high voltages applied across its electrodes.